Process for preparing n-alkylthioalkyl-o-alkylthiocarbamates and n-alkyl-thioalkyl-o-alkylcarbamates

ABSTRACT

COMPOUNDS OF THE FORMULA   R-O-C(=Z)-NH-CH(-R&#34;)-CH2-S-R&#39;&#39;   WHEREIN Z IS OXYGEN OR SULFUR, R AND R&#39;&#39; ARE HYDROCARBYL RADICALS AND R&#34; IS HYDROGEN OR LOWER ALKYL, ARE PREPARED IN THE NOVEL PROCESS COMPRISING REACTING (A) A COMPOUND OF THE FORMULA   THE COMPOUNDS ARE USEFUL IN THE FLOTATION OF SULFIDE ORES.   HN&lt;(-CH(-R&#34;)-CH2-)   WITH (B) AN AZIRIDINE OF THE FORMULA   R-O-C(=Z)-S-R&#39;&#39;

United States Patent O 3,772,345 PROCESS FOR PREPARING N-ALKYLTI-IIOALKYL, O-ALKYLTHIOCARBAMATES AND N-ALKYL- TIHOALKYLrO-ALKYLCARBAMATES George E. Ham and Benjamin V. Alcala, Lake Jackson,

Tex., and Guy H. Harris, Concord, Calif., assignors' to The Dow Chemical Company, Midland, Mich.

"' Filed Sept. 8,.1970, Ser.'No. 70,399

Int. Cl. C07c 155/08 US. Cl. 260-455 A 9 Claims ABSTRACT OF THE DISCLOSURE Compounds of the formula V Ro-b- NH-onm-ortr-s-R' wherein Z is oxygen or sulfur, R and R are hydrocarbyl radicals and R" is hydrogen or lower alkyl, are prepared in the novel process comprising reacting (a) a compound of the formula n-o-b-s n' with (b) an aziridine of the formula The compounds are useful in the flotation of sulfide ores.

BACKGROUND OF THE INVENTION The use of the title compounds as flotation agents in the recovery of metal values from sulfide ores was set forth in a commonly owned US. patent application, Ser. No. 799,119, entitled Flotation of Sulfide Ores, filed Feb. 13, 1969. It is now US. Pat. 3,590,999.

SUMMARY OF THE INVENTION The invention is a process for preparing compounds represented by the formula R NH-CHR"CH2SR' wherein Z is oxygen or sulfur; R is alkyl, cycloalkyl or aralkyl or preferably from 1 to about8 carbon atoms; R is alkyl, cycloalkyl, aralkyl or aryl of preferably from 1 to about 8 carbon atoms; and R is hydrogen or lower alkyl of from 1 to about 4 carbon atoms. The novel process comprises reacting (a) a compound of the formula R-o-l :s-R'

wherein Z, R and R have the above meaning, with (b) an aziridine of the formula The reaction temperature is suitably from about 0 C. up to the decomposition temperature of the product. In mostinstances, about 180 C. is a practical upper limit. At temperature of from about 20 C. to about 80 C. is pre-- ferred. The reaction temperature may be conveniently regulated by the rate of addition of one of the reactants to the reaction mixture, preferably the aziridine reactant.

. The reaction pressure is not critical and may be varied to convenience. Atmospheric or superatmospheric pressures typically used.

The reaction is preferably conducted in liquid phase.

The reaction rate is generally high. Reaction times of from about 5 minutes to about 5 hours are generally suflicient for the reaction to proceed to substantial completion.

The reaction is preferably conducted in the presence of a catalytic amount of a tertiary amine. Such amines include trialkyl amines, such as trimethyl-, triethyl-, tributyl-, trihexylamine, and the like; heterocyclic amines, such as N-methylmorpholine, N,N-diethylpiperazine, pyridine; weak-base, anion exchange resins, such as the condensation polymers of epichlorohydrin and ammonia; aralkyl amines, such as tribenzylamine, N,N-dimethylaniline, benyl dibutylamine; and other like amines. Such amines, when present, are usually included in amounts of from about 0.1 to about 15 percent by weight, total reactant basis.

SPECIFIC EMBODIMENTS The following examples further illustrate the invention.

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EXAMPLE 1 N-methylthioethyl-O-isopropylthiocarbamate Several runs were conducted wherein ethylenimine (E1) was added to a mixture of methyl isopropyl xanthate (MIX) and triethylamine (TEA) The process parameters and experimental results are set forth in FIGS. 1-3 and in the discussion below. Experimental results are expressed as percent yield of product based on converted reactant, either MIX or EI.

In FIG. 1, the mole ratio of EI/TEA was 10, the reac tion temperature was maintained at about C. for a total reaction time of 2 hours. The process variable was the mole ratio of MlX/EI.

In FIG. 2, the mole ratio or MIX/EI 'was 1.5, the reaction temperature was maintained at about 60 C. for a total reaction time of 2 hours. The process variable was the mole ratio of MIX/TEA.

In FIG. 3, the mole ratio of MIX/EI was 1.5 and the mole ratio of MD(/TEA was 10. The process variable was time at three temperatures.

The following experiments are conducted in like manner and in accordance with the equation The products are flotation agents. We claim:

1. A process for preparing a compound of the formula II RO-C-SR' wherein Z, R and R have the above meaning with (b) an aziridine of the formula having the above meaning.

2. The process defined in claim 1 wherein the molar ratio of (a):(b) is from 5:1 to 1:5.

3. The process defined in claim 1 wherein the molar ratio of (a):(b) is from 1.5:1 to 121.5.

4. The process defined in claim 1 wherein said process is conducted in the presence of a catalytic amount of a tetriary amine catalyst.

5. The process defined in claim 1 wherein Z is sulfur.

6. The process defined-in claim 1 wherein R is alkyl, cycloalkyl or aralkyl of from 1 to about 8 carbon atoms, and R is alkyl, cycloalkyl, aralkyl or aryl of from 1 to about 8 carbon atoms.

7. The process defined in claim 1 wherein R" is hydrogen.

8. The process defined in claim 1 wherein said temperature is from about 20 C.'to about C.

9. The process defined in claim 8 wherein Z is sulfur, R is isopropyl, R is methyl, R" is hydrogen; the molar ratio of (a):(b) is from 1.5:1 to 111.5; and said process is conducted in the presence of a catalytic amount of triethylamine.

References Cited UNITED STATES PATENTS 2,785,191 3/1957 Schwyzer 260-455 A 3,410,893 11/1968 Levine 260481 C 2,824,857 2/ 1958 Dreschel 26077.5

3,436,305 4/1969 Maher 117-156 FOREIGN PATENTS 718,063 11/1954 Great Britain 260-561 1,942,676 3/ 1970 Germany 260455 A LEWIS GOTTS, Primary Examiner G. HOLLRAH, Assistant Examiner US. Cl. X.R.

209166; 260455 B, 468 C, 470, 481 C i UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 3,772,345 I Dated November 13; 1973 lnventofls) George .E, Ham, Benjamin V. Alcarla. end Guy H. Harris v It is certified that error appears in the above identified patent and that said Letters Patent are hereby correctedes'shown below:

Col. 2, line 1 0; Insert -are--between "sures" and "typically". I

Col. 2, line 23; Change '?beny l", to --be Y 61am '1, a e i 10:1 C( hange "a1ky,-", 't5'-"--a 1k 1,--. Cle ir n l, 3, line 24: Insert R"-- before "having";

'Col. 4, line; 2o= Chang e "i'Dreschel" to -Dr'echsel- Signe drandseal-ed this 3rd day of-Deeember 1974.

(SEALI Att'est: r I I v McCOY M. c'ls'sm JR. v C MARSQALL-DANN I Attestingf Officer l -Conm\iss1oner of Patents 

